Abstract: The focus of this study was to identify and describe bryophyte-environment
relationships in wetland swamp forests of the Northeast Cape Fear River, southeastern
North Carolina. A total of 44 genera consisting of 39 moss species and 21 liverwort
species were identified. There was one new liverwort recorded not previously described
from North Carolina, Cololejeunea setiloba. The diversity of bryophytes in the swamps
of the Northeast Cape Fear River was higher than expected observations.
Bryophyte densities and species richness were compared to flood depth relative to
the swamp surface, salinity, and elevation of the swamp surface for three sites each with
six substations within a transect from riverbank to upland edge. There was a general
trend of an increase in bryophyte density and species richness as flood depth and salinity
decreased from river to upland.
Principal component analysis used 13 environmental variables, ranging from
transect distance upriver, substation distance from river’s edge to base of upland,
hydrology, elevation, duration of flooding, and salinity. These environmental variables
accounted for much of the variation in the abundance of bryophyte species. A principal
component biplot showed clustering between species of bryophytes with correlation
between certain species and their tolerance for specific stress-related environmental
variables.
The majority of the bryophytes sampled were not common in the study system
and have narrow habitat specificity. Although bryophytes may form a major part of
several vegetation types and ecosystems, in this study, relatively few bryophyte species were ecologically abundant or dominant. Isopterygium tenerum is one occurring
commonly and over a wide range of habitats.
Fontinalis sullivantii, a facultative aquatic bryophyte, in the Northeast Cape Fear
River can clearly tolerate low salinity water. It occurs along exposed roots and bases of
trees, such as bald cypress. It is submerged at rising and high tide and partially exposed
at low tide therefore exposing it to varying salinity as well as desiccation. High salinity,
in the range between 5 and 15 ppt, significantly reduced photosynthetic efficiency of the
moss species, Fontinalis sullivantii, on the short time scale, followed by some recovery.
Desiccation after approximately 3 hours also reduced photosynthetic efficiency.
However, observed physical changes in the disappearance of Fontinalis sullivantii due to
a major drought suggests a strong relationship between increasing salinity and
disappearance of this species.
Long term implications of the current study are that bryophyte data will be used to
assess future impacts due to current dredging projects in the Cape Fear River estuary.